Air compression for self-ignition engines



Feb. 16, 1960 s. MEURER 2,925,070

- AIR COMPRESSION FOR SELF-IGNITION ENGINES Filed June 9. 1958ATTORNEYS" miin United States Patent 6 AIR COMPRESSION FOR SELF-IGNITIONENGINES Siegfried Meurer, Nurnberg, Germany, assignor to MaschinenfabrikAugburg-Nurnberg A.G., Nurnberg, Germany Application June 9, 1958,Serial No. 740,928 Claims priority, application Germany, June 15, 1957Claims. (Cl. 123-32) This invention relates to the air compression inselfignition internal combustion engines. In particular, the

invention is directed to the means for compressing the film of fuel tovaporize the same, with these vapors in turn being ignited by theself-ignited atomized fuel.

In such an engine, combustion air is present in the combustion chamberand also in the compression space of the cylinder wherein the air is ata lower pressure during the period of combustion than the gas pressurewithin the combustion chamber. The low pressure area or areas areprincipally at the pockets in which the valves are seated. By reason ofthe lower pressure, the air, especially that in the valve pockets, iseither not, or just slightly, exposed to the fuel mixture formed in thecombustion chamber and the following combustion process. Anunsatisfactory condition therefor exists because these low pressurespaces can contain as much as about 20% of the total volume of thecombustion air. This means that of the total combustion air some 20%either doesnot enter into the combustion process or is inefiicientlyused therein.

The objects of this invention are to produce a structure and process foravoiding the above disadvantages and to utilize effectively thecombustion air contained in the low compression space.

In general, the objects are obtained by forming a channel or passagewayconnecting the combustion chamber and the low pressure area in thecylinder, such channel being directed especially toward the valvepockets.

During the combustion process or burning of the gas in the combustionchamber, a current of gas is formed in the channel directed toward thecylinder space for a low pressure area. This gas current carries a partof the fuel from the combustion chamber and delivers it to the lowpressure area. The fuel thereupon mixes with the low pressure air andwill thereupon burn. Consequently, the low pressure air, andparticularly the air in the valve pockets, takes part in the fuelcombustion process.

For example, it is known to form channels between a combustion chamberin a piston and direct them toward the valve pockets. But in such aconstruction, these channels are not for the purpose of those of thisinvention. These prior art channels are for the purpose of assisting inthe scavenging of the exhaust gases from the cylinder, whereas thechannels of the present in vention are for transferring fuel from thecombustion chamber to the valve pockets in order to utilize the lowpressure air for purposes of combustion.

According to another feature of this invention, the

channels extend from the area of the point of contact of the fuel jetupon the wall of the combustion chamber. This ensures with considerablecertainty that a sufficient amount of fuel is transferred to the areasof low pressure air. If the cylinder compression space has several zonesin which a lower air pressure exists than the pressure in the combustionchamber, a separate channel can be directed to each area. For example,in an engine having four valves for each cylinder, a separate channelcan be directed toward each of the four valve pockets.

The means by which the objects of the invention are obtained aredisclosed more fully with reference to the accompanying drawings, inwhich:

Figure 1 is a plan view of a piston head with the position of the lowpressure pockets adjacent the valve seats and the fuel nozzle beingschematically indicated;

Figure la is a fragmentary view of Figure 1 showing a modification inthe location of the channel;

Figure lb is a view similar to Figure 1 of a further modification; and

Figure 2 is a cross-sectional view through a portion of the cylinder andcylinder head showing the piston of Figure l in the cylinder.

As shown in Figures 1 and 2, the piston 1 contains a combustion chamber2 formed as a body of rotation as, for example, a sphere. Thiscombusition chamber has a cylindrical neck portion 3 extending throughthe surface of the piston head and communicating with the cylinder space4 within cylinder 5. Obliquely mounted in cylinder head 6 is a fuelinjection nozzle from which fuel is injected through neck 3 of thechamber 2. The injected fuel is in the form of several concentrated jets8 of short length which are directed at a sharp angle toward the wall ofchamber 2 in order to form a film 9 on the wall. By so doing, up to 98%of the fuel is deposited as a film on the wall. The remainingapproximate 2% of the fuel which is at a maximum that which gives a justnoticeable ignition noise during running of the engine is atomizedimmediately in the combustion air. Such atomizing is achieved either bysuitably deflecting a part of the fuel jets or by means of a speciallydirected jet in the combustion chamber, the latter not being shown. Thecompression ratio in the cylinder is fixed so that the atomized air iscertain to be self-ignited, but the fuel on the combustion chamber walldoes not ignite. The combustion air is swirled as it enters the cylinderas indicated by the arrow x in the same direction as the fuel jets 8.This air vaporizes the fuel from the film 9 on the chamber wall.Ignition and the following combustion thus proceed according to theengine in aforesaid application No. 480,432.

Beneath valves 12 and 13 and especially in the valve pockets 14 and 15,a volume of air 16 exists at the top dead center position of piston 1.During the combustion of the fuel in chamber 2, the volume of air 16 isat a lower pressure than the pressure in the combustion chamber. Toinclude the low pressure air in the combustion process, a passageway orchannel 17 is provided in piston 1. This channel extends from the areaof the contact of fuel jets 8 on the chamber wall to the top surface ofthe piston and thus forms a communication between the combustion chamberand the air volume 16 in the area of valve pocket 14. Because of thepressure difference between the gas in chamber 2 and the air volume 16,a gas flow of current as indicated by arrow 18 takes place in channel 17while the combustion or burning of the gas proceeds in chamber 2. Thedirection of this current 18 is from the combustion chamber outwardlytoward air volume 16. This current carries a part of the fuel fromchamber 2. This fuel reaches air volume 16 to form an airfuel mixturetherewith which will burn. Thus the residual air volume 16 is broughtinto and takes Patented Feb. 16, 1960 part in the combustion process.The quantity of fuel carried into air volume 16 is determined by thecurrent 18 which in turn is determined by the size and position ofchannel 17. As-determined -by-the quantity of fuel required in airvolumeqlfi,the-directionof channel 17 can be radial with respect toFigure 2 as shown in Ei ures l and 2, in thesame direction-of the airswirl mas shown by the channel 17a of Figure 1a, ;or against the airswirl x as shown by the channel 17b of- Figure 1b.

Furthermore, the channel 19, v l-"t igure 2, similar to channel ;17 ,isprovided for forming communication with the airpocket 115 beneath valve13. I

The channels of this invention are also used ltofix the volume of theair-distributed portion :of the injectedfuel.

This is done by making-the size of the channels eitherv at cylinderhead,intake and exhaust valves ,in.said head and forming low pressure areasin said cylinder, apiston movable in said cylinder to compress thecombustion'air, a combustion chamber in said piston and opened throughthe top surface of said piston meansfor forming an unidirectional airswirl in said chamber from the compressed combustion air, and a fuelnozzle positioned to inject the major portion of the fuel against thewall of said vchamher to form a film thereon, the improvement comprisinga channel extending from said combustion chamber through the uppersurface of said piston and directed toward a valve for transferring fuelvaporized in said chamber to a lower pressure area in saidcylinderadjacent said valve. 7

2. In an engine as in claim 1, said channel extending 4 from the impactarea of the fuel jet with the wall of said chamber.

3. In an engine as in claim 1, further comprising a separate channeldirected to each of the valves in said cylinder head.

4. A method of burning fuel in an internal combustion engine having acylinder, :and a combustion space associated therewith, comprisingimparting a swirling motion in one direction to the intake air durng thecompression stroke, injectingastream of fuel into said space near topdead center of the compression stroke in substantially "the samedirection as said air swirl and with the major portion of the fuel beingdeposited'on the wall of the combustion space as a non-vaporized filmand a minor portion of the fuel atomized in said air swirl,igniting'said minor portion of the fuel at approximately the top deadcenter of the compression stroke, continuing the air swirl in the same.direction during the powerstroke while progressively vaporizing andburning the fuel from said film, and simultaneous with said vaporizingtransferring a portion of the vaporizedfuel from the high combustion gaspressure area of said chamber to a lower pressure air areain saidcylinder. 7 g

,5. A method as in claim 4, said transferring of vaporized fuel beingfrom a combustion chamber in a piston to a low pressure air pocketadjacent a valve for said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS LiebelApr. 29, 1958 Cu 9 t

